Submission #800396

#	Time	Username	Problem	Language	Result	Execution time	Memory
800396		Dan4Life	Sorting (IOI15_sorting)	C++17	20 / 100	1 ms	468 KiB

sorting

#include "sorting.h"
#include <bits/stdc++.h>
using namespace std;
const int mxN = (int)2e5+10;
int n, tot, a[mxN], t[mxN], x[mxN], y[mxN], pos[mxN], vis[mxN];
 
void swp(int i, int j, int P[], int Q[], bool ok=0){
    if(i==j) return;
	if(ok) P[tot]=i, Q[tot]=j, tot++;
	swap(pos[a[i]],pos[a[j]]); swap(a[i],a[j]); 
}
 
int chk(int m, int P[], int Q[]){
    for(int i = 0; i < n; i++) a[i] = t[i], vis[i]=0, pos[a[i]] = i;
    for(int i = 0; i < m; i++) swp(x[i],y[i],P,Q), P[i]=Q[i]=0;
    tot = 0; fill(vis,vis+n,0);
    for(int i = 0; i < n; i++){
		if(vis[i]) continue; 
        int j = i; vector<int> v; v.clear();
		while(!vis[j]) v.push_back(j), vis[j] = 1, j = pos[j];
		for(int i = 0; i < (int)v.size()-1; i++) swp(v[i],v[i+1],P,Q,1);
    }
    return (tot<=m)?m:mxN;
}
 
int findSwapPairs(int N, int A[], int m, int X[], int Y[], int P[], int Q[]) {
    n = N;
    if(is_sorted(A,A+n)) return 0;
    for(int i = 0; i < n; i++){
        a[i] = t[i] = A[i];
        x[i] = X[i], y[i] = Y[i];
    }
    int l = 0, r = n;
    while(l<r){
        int mid = (l+r)/2;
        if(chk(mid,P,Q)<=mid) r=mid;
        else l=mid+1;
    }
    return chk(l,P,Q);
}

Compilation message (stderr)

sorting.cpp: In function 'int chk(int, int*, int*)':
sorting.cpp:21:11: warning: declaration of 'i' shadows a previous local [-Wshadow]
   21 |   for(int i = 0; i < (int)v.size()-1; i++) swp(v[i],v[i+1],P,Q,1);
      |           ^
sorting.cpp:17:13: note: shadowed declaration is here
   17 |     for(int i = 0; i < n; i++){
      |             ^
sorting.cpp: In function 'int findSwapPairs(int, int*, int, int*, int*, int*, int*)':
sorting.cpp:26:39: warning: unused parameter 'm' [-Wunused-parameter]
   26 | int findSwapPairs(int N, int A[], int m, int X[], int Y[], int P[], int Q[]) {
      |                                   ~~~~^

• Subtask 1: 8 / 8
• Subtask 2: 12 / 12
• Subtask 3: 0 / 16
• Subtask 4: 0 / 18
• Subtask 5: 0 / 20
• Subtask 6: 0 / 26